MIT researchers have uncovered a critical difference between flu viruses that infect birds and humans, a discovery that could help scientists monitor the evolution of avian flu strains and aid in the development of vaccines against a deadly flu pandemic.

Scientists have identified a key factor that determines the ability of influenza viruses to infect cells of the human upper respiratory tract—a necessary step for sustaining spread between people.

Starting with blood of patients who survived a bout of avian flu (infection with the H5N1 strain), Cameron Simmons (of the Oxford University Clinical Research Unit at the Hospital for Tropical Diseases in Ho Chi Minh City, Vietnam) and colleagues generated neutralizing human monoclonal antibodies and show that they can halt viral growth in mice deliberately infected with H5N1 virus.

Scientists here have designed a new, interactive map of the spread of the avian flu virus (H5N1) that for the first time incorporates genetic, geographic and evolutionary information that may help predict where the next outbreak of the virus is likely to occur.

For avian influenza, the analyses show that there are two poultry-dense areas in The Netherlands where epidemic spread is possible, one in the central region and one in the south, close to the German and Belgian border (see attached figure). The authors suggest local control measures are unlikely to be able to halt an unfolding epidemic in these areas.